That took a while.
Yes, there is. Or, are.
You know, Ember doesn't exist as a move in the Smogon Damage Calc, and Kartana is unreleased in others.
So I gave up. Almost. My curiosity won over and tried it methodically.
Bagon is the Pokemon that can learn Ember with the least Special Attack, and it doesn't even get STAB. And lo and behold, it causes only 53% damage.
For good measure, I added the Pokemon with the next least Special Attack, Fletchinder, which gets STAB. At Joly nature, Kartana still survived w/ 8% health.
All Pokemon were Jolly in nature.
I realise you gave two scenarios, but I got only till playing out one. Hope you don't mind.